Snap action push button switch



Aug. 13, 1957 P. HUTT 2,802,915

SNAP ACTION PUSH BUTTON SWITCH Filed Dec. 1', 1955 arma f/vz/e/yfor 1A05 Ammg United States Patent O 2,802,915 SNAP ACTION PUSH BUTTON SWITCHPhilip Hutt, Milford, Conn., assignor to General Electric Company, acorporation of New Yeti;

f Application December 1, 1955, Serial No. 550,253

7 Claims. (Cl. 200-67) cooperation with a pair of slides to eifect theopening and closing of a series of preselected electric circuits uponthe actuation of the buttons.

This invention is an improvement in the push button switch of the basictype exemplified by the Andrews Patent No. 2,431,904 which is assignedto the same assignee as is the present invention. The Andrews switch wasdesigned for alternating current useonly, and it has been widelyaccepted and extensively used for many years for controlling the heatingelements of electric ranges.

I' have now'developed a push button switch having movable slides with anover-center snap acting mechanisni so that the switch may be used onboth direct and alternating currents. The switch illustrated in thedrawing has been developed particularly for use with portable lamps forthe control of a two filament, threeway lamp. However, it should bereadily understood that this invention is not limited to the particularembodiment disclosed nor to the exact use indicated. My invention ispreferably encased in a hollow switch housing comprising a recessed baseand an insulating cover plate. A plurality of push buttons extendthrough openings in the bottom wall of the base while apairof'slides'are arranged alongside the buttons to be controlled thereby.Each slide contains a series of cam surfaces which cooperate with a camfollower on each button to move the slides inendwise directions in amanner'similar to that of the Andrews patent. In addition, a commonterminal bar is mounted in an opening in the side wall of the baseopposite from the buttons. A pair of fixed contacts are also mounted inthe housing, each with its terminal portion mounted in an opening in thesaid side wall, one on each side of the terminal bar. A pair of movablecontacts of generally Z-shape are hung'frona spaced points on theterminal bars so that they may oscillate into and out of contact withthe fi'xedcontacts. In order to elfect the quick opening and closing ofthe contacts, an over-center spring is supported at the lower end ofeach movable contact while it bears against an overhanging arm extendingfrom one of the slides. Thus, when a button is depressed, one ormore ofthe slides moves in an endwise direction thereby displacing theoverhanging arm to compress the over-center spring until the movablecontact is shifted to its opposite position.

' An'important advantage of my invention is that the overfcenter springexerts a force that is offset from the pivotal support point for themovable contact so that the force supporting the movable contact and theforce exerted by the over-center spring constitute a couple and tend tohold the swinging end of the movable contact toward the adjacent'sidewall of the base. This tends to give a strong wiping action between themovable contacts and fixed contacts thereby cleaning any carbon2,802,915 Patented Aug. 13, 1957 2 deposits, oxides or dirt formationsfrom the contacts that might increase the resistance of the circuit andcause excessive operating temperatures.

Accordingly, it is the principal object of this invention to provide amultiple push button switch with a snap acting mechanism so that theswitch may be used in both direct and alternating current circuits.

A further object of this invention is to provide a multiple push buttonswitch with movable slides that are connected with the movable contactsof the switch through an over-center spring mechanism for effecting asnap action. 7

A still further object of this invention is to provide a push buttonswitch with a snap acting mechanism which exerts a strong force to wipethe movable contact across the fixed contact for more reliable switchoperation.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing and its scope will bepointed out in the appended claims.

In the drawing:

Figure 1 is a plan view of a switch embodying my invention with thecover plate removed.

Figure 2 is an exploded view showing the spatial relationship betweenthe movable parts of the switch.

Figure 3 is a cross-sectional elevational view taken on the lines 3-3 ofFigure 1.

Figure 4 is a diagrammatic View showing the positions of the buttons,slides and movable and fixed contacts when the third button from theleft is depressed.

Figure 5 is a view similar to that of Figure 4 except the extremeleft-hand button has been depressed.

Referring in detail to the drawing, 10 represents a hollow switchhousing of insulating material. This housing is. formed by the deeprecessed base 11 and the flat cover plate 12 which are held together bymeans of the metal strap 13. The ends 14.of the strap are bent underinto depressions at the ends of the base to hold the strap in place.Looking at the plan view of the base of Fig ure 1, four push buttons 15are arranged along the side wall 16 of the base. T-shaped partitions 17are formed between each button and are in cooperation with the sidewings 18 of the buttons to limit the movement of the buttons to areciprocating movement. These wings 18 do not extend the full length ofthe buttons as seen in Figure 2 for they are totally enclosed within thebase to serve as stop means to prevent the removal of the buttonsthrough the bottom wall of the base. Abutments 19 extending from the endwalls of the base cooperate with the side wings 18 of the two endbuttons to complete the guiding means for th buttons in the base.

Looking at Figure 2. of the drawing there is shown a pair of metalslides 20 arranged side by side and each having a series of four camsurfaces 21 in a longitudinally spaced relationship. Each push button 15is shown with a pin-like cam follower 22 which cooperates with the camsurfaces 21 of the slides to effect the endwise movement of the slidesin a well-known manner as will be explained hereinafter. In Figure 1 theslides 20 are shown positioned in the grooves 23 at the ends of the baseformed by the opposite partitions 19 and 24. The slides are furthersupported in the base by means of the central transverse partition 25that also separates the remainder of the base into two switchingchambers 2 6 o e mou n the'base a d a Pair of side s ha inc ude a k ifee ge 35 eparat ng a pai o p standing fingers 36. Each terminal portionis provided with a tapped opening 37 for receiving a binding screw 7(not shown) therein. The movable contacts 38 are formed of thin stripmaterial which is bent transversely into a generally Z-shape.- The upperarm '39 ofeach movable contact is adapted to pivot .on the'knife edge 35of the terminal bar 30. Side extensions 40 are likewise included as partof the upper arm 39 of the contact to engage behind the fingers 36 ofthe terminal bar to hold the movable contact from slipping out ofposition. The lower arm or distal end 41 of the contact 38 serves as aspring seat having an oversized aperture 42 into which a spring guiderod 43 may be loosely inserted. A stop means 44 is arranged near thebottom of the guide rod 43 to prevent the rod from I slipping completelythrough the aperture 42 while serving as a rocking knife edge supportfor the lower end of a coil spring 45 that is assembled over the rod. Ofcourse it will be understood that the guide rod 43 could also beassembled with the stop means 44 reversed in position at the top of theswitch. In some applications this would be preferred.

An overhanging arm 46 is formed adjacent the top edge of each slide tobe longitudinally spaced from each other. An oversized aperture 47 isformed in each arm to receive the upper end of the guide rod 43 so thateach spring 45 is confined between the lower arm 41 of one movablecontact and the related overhanging arm 46 of the slides. The sides ofthe free end of the overhanging arm 46 are formed upwardly as at 48 tolie in the same horizontal plane as the top edges of the slides 20 sothat the cover plate 12 serves to hold the slides firmly down in thebase against the resistance of the coiled springs 45.

Turning again to a consideration of Figure 1, it should be appreciatedthat openings are formed in the top edge of the side wall 50 of the baseopposite the side 16 for accommodating the terminal bar and terminalportions 32 of the fixed contacts 31. For example, the

central portion 33 of the terminal bar 30 is shown supported in the sidewall by means of opposed grooves 51 while the terminal portions 32 ofthe fixed contacts are held in opposed grooves 52 in a well-knownmanner.

Hence, it will be appreciated that as the slides 20 move backward andforward from end to end of the base'the upper spring seat 46 will shiftto first compress the spring until the upper spring seat passes beyondthe longitudinal center line of the movablecontact whereby the springwill tend to expand and force the movable contact into its oppositeposition.

Looking now at Figure 4 of the drawing, the slide 20 that is arrangednearest the buttons 15 is shown for illustration purposes at the topwith the other slide 20 arranged directly underneath. A cam follower 22of each button is shown in cooperation with the cam surfaces 21 of theslides, while both of the movable contacts 38 extend in a parallelrelationship, there being a closed circuit between the right-handmovable contact and its related fixed contact 31.

In Figure 5 the switch elements have shifted as a result of theactuation of the left-hand button 15. This can be better understood byreferring first to Figure 4 where it is seen that the cam follower 22 ofthe lefthand button is associated with the inclined surface 55 so thatas that button is depressed, the cam follower will act against surface55 to shift the lower slide to the right. Likewise, there is a reverselyinclined surface 56 in cooperation with the cam follower of the thirdbutton from the left. Thus, when the lower slide moves to the right, thethird button which had been previously depressed would be forcedoutwardly as shown in its final position in Figure, 5. In the upperslide of Figure 4. the cam surface 21 related to the left-hand buttonhas a vertically extending concave surface 57. This surface 57 doesshift the upper slide a slight amount but the 4 force of the compressionspring 45 is enough to return the slide to its original position as seenin Figure 5.

The downward force exerted on each movable contact 38 by the coiledspring 45 and the upward force at the knife edge 35 of the terminal bar30 form a couple tending to rotate the movable contact in a planeperpendicular to the side wall 50 of the base. This rotation is resistedby a counter couple comprising a force exerted by the spaced fingers 36resisting the side extensions 40 of the upper arm 39 of the contact andan additional force exerted against the lower portion of the contactwhere there is a wiping engagement with the fixed contact. In otherwords,-the lower engaging surface of the movable contact 38 bearsstrongly against the fixed contact 31 or the adjacent inner walls of theside wall 50. This arrangement provides a very important feature thatdirt, carbon deposits, and oxidation which naturally form on thecontacts will be wiped clean by this rubbing action to result in a moredependable switch.

Having described my invention above it will be readily appreciated bythose skilled in this art that I have devised a novel snap actingmechanism in cooperation with a multiple push button switch to effectthe vquick opening and closing of the contacts. I have arranged theswitch elements so that theyall may be assembled in the base, making ita simple matter to install the cover plate and the mounting strap forholding the parts together. The parts are few in number and either ofmolded or stamped construction so that they may be made by mass.production methods and quickly assembled with unerring accuracy.

Modifications of this invention will occur to those skilled in this art;therefore, it is to be understood that this invention is not limited tothe particular embodiment disclosed but that it is intended to covervallmodifications which are within the true spirit and scope of thisinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A push button switch comprising a hollow housing; a plurality of pushbuttons extending through onc..wal1 of the housing, a pair of slides inparallel engagement, each slide having a series'of cam surfaces,and acam follower on each push, button cooperating with aligned cam surfacesin each slide so that the depression ofa push button effects the endwisemovements of one or more slides, fixed contacts mounted on a side wallof the housing that is parallel with the said slides, and movablecontacts each pivotally hung by one end from a terminal plate on saidside wall, and a compression spring held between an overhanging arm ofeach slide and the distal end of its related movable contact to serve asan over-center snap acting mechanism. v

2. A push button switch comprising a recessed base and a cover plate, aplurality of push buttons extending through openings in the bottom wallthere'of,a' pair of metal slides arranged alongside the buttons, and aseries of cam surfaces in each slide in cooperation with a cam followeron each button for effecting the endwise movements of the slides in apredetermined manner, a common terminal bar mounted in an opening in theside wall of the base opposite the buttons, and a pair of inovablecontacts of generally Z-shape each hung byone end for pivotal movementat spaced points on the terminal bar, a pair of fixed contacts disposedat opposite sides of the terminal bar with their terminal portionsmounted in openings in said side wall of the base, an overhanging arm atthe top edge of each slide, and a compression spring supported betweeneach arm and the distal end of the adjacent movable contact to serve asan CV61". center snap acting mechanism between the slides and themovable contacts. 7 v

3. A multiple push button switch comprising a hollow housing with a pairof slides arranged for endwise movements and controlled by the operationof the buttons in a predetermined manner, a pair of fixed contactsmounted on a side wall of the housing that is parallel with the saidslides, and a pair of swinging contacts each hung by one end from aterminal bar that is fixed on the same side wall of the housing, anover-center snap acting mechanism for each swinging contact supportedbetween a transversely extending arm of a slide and the opposite end ofits related swinging contact to cause the quick opening and closing ofthe contacts.

4. A multiple push button switch comprising a hollow housing with atleast one slide arranged for endwise movement and controlled by theoperation of the buttons in a predetermined manner, a fixed contactmounted in the housing, and an oscillating contact pivotally suspendedat one end on a terminal bar and movable into and out of engagement withthe fixed contact, and an over-center spring mechanism comprising a coilspring and a guide rod supported between the swinging distal end of themovable contact and an arm at the top edge of the slide to efiect thequick opening and closing of the contacts.

5. A push button switch as recited in claim 4 wherein the pivotalsupport for the movable contact is off-set from the longitudinal axis ofthe spring to force the distal end of the movable contacts into rubbingengagement with the fixed contact.

6. A push button switch as recited in claim 5 wherein the movablecontact is of thin strip material that is folded transversely into agenerally Z-shape having an upper and a lower arm, the upper arm ofwhich rests on a knife edge on the terminal bar for rocking movement,the outermost extremity of the upper arm having side extensions whichcooperate with upwardly extending fingers on the terminal bar atopposite sides of the knife edge to prevent their accidentaldisengagement,

7 A push button switch as recited in claim 6 wherein the lower arm ofthe movable contact has an enlarged opening for receiving the lower endof the spring guide rod, said rod having a stop means adjacent said endto serve as a rocking seat between the lower end of the spring and thelower arm of the movable contact, the upper end of the guide rodextending through an enlarged opening in the said arm at the top edge ofthe slide.

References Cited in the file of this patent UNITED STATES PATENTS1,587,837 Hopkins June 8, 1926 1,819,831 Whalen Aug. 18, 1931 2,078,253Krieger Apr. 27, 1937 2,431,904 Andrews Dec. 2, 1947 FOREIGN PATENTS607,501 Great Britain Sept. 1, 1948

